The precise description of cardiovascular geometry has challenged embryologist, anatomist, and biologist for centuries (van Mierop 1979). Attention has focused on early cardiac morphogenesis because of the relationship between cardiac functions and form (Clark 1990). Experimental methods to image the embryonic heart include light, confocal laser, and electron microscopy, cinephotography, and videography (Faber 1974, Keller 1990). Normal cardiac morphogenesis has been described for the chick, mouse, rat, dog, and human; however, the primary model for the experimental investigation of the cardiac morphogenesis in the chick embryo (Pexieder 1984, 1986). Despite the ability to image embryonic structures, investigators have not identified the fundamental mechanisms which determine the interaction between form and analyzed with respect to a single structural aspect. While the external shape of the heart has been qualitatively defined normal morphogenesis or following specific experimental interventions, the analysis of global structure has not been coupled to an analysis of tissue, cellular, and subcellular architecture (Manasek 1979). The long term aim of the Morphometry Core is to provide state of the art resources for the structural assessment of normal and altered cardiovascular development. The experimental model for this grant period is the stage 10 to 29 white Leghorn chick embryo. The specific aims of this Morphometry Core are: Acquire and transform into a uniform format images of embryonic cardiovascular structures from video recordings, confocal laser microscopy, and scanning electron microscopy. Optimize cardiovascular image features using standard and state of the art image analysis techniques. Analyze cardiovascular images for global geometry, regional geometry including cell to cell and extracellular components in regions of interest, and myofiber maturation and alignment. Reconstruct the 3-dimensional geometry of the embryonic cardiovascular system for the refinement of engineering models of the developing cardiovascular system, and for the graphical display of regions of interest. The Morphometry Core provides all of the resources necessary to acquire and analyze images of the embryonic heart. The experimental design of each project includes specific Guiding Hypotheses, proposed Experiments, and preliminary Interpretations. Thus, the Morphometry Core provides a state of the art resources for image acquisition, optimization, analysis, and reconstruction to complement the experimental investigation of normal and altered cardiovascular morphogenesis.